This invention relates to projection systems, and in particular, to a projection system adaptable for use in flight simulators. While the projection system is described with particular detail in conjunction with its flight simulator application, those skilled in the art will recognize the wider applicability of the inventive principles disclosed hereinafter.
The art of flight simulation has developed to the point where the flight simulators offer sound, motion and visual cues for research, engineering development and pilot training applications that closely approximate actual flight conditions. Among known simulator systems is one in which several projectors are used, including projectors which are behind the display system. More recently, systems have been designed which use two projectors to essentially fill a 360.degree. dome. Art which relates to this simulation technique include (i) the U.S. patents to Pund, U.S. Pat. No. 4,167,311, (ii) U.S. Ser. No. 254,417, filed Apr. 15, 1981, now U.S. Pat. No. 4,427,274 and U.S. Ser. No. 428,169, now U.S. Pat. No. 4,515,450 filed Sept. 29, 1982, all assigned to the assignee of the present invention. The disclosures of each of the patents and applications are incorporated herein by reference. The invention disclosed hereinafter is intended to be compatible with certain aspects of those systems. However, it also provides additional flight cues to the operator of the simulator by generating a dynamic earth/sky interface which changes with altitude, attitude, and horizontal position over the terrain of the simulated flight so that the scene presented to the operator changes dynamically in a realistic manner. The earth/sky and cloud interface is accomplished simply and more economically than known prior art devices.
One of the objects of this invention is to provide an image generation system supplying imagery to a projection system which is capable of projecting an image from a single projector onto an extremely wide field so as to cover a very large display area with imagery, that imagery including a dynamic earth/sky interface.
Another object of this invention is to provide an image generation system which is particularly suitable for use in providing imagery to a projection system for projecting realistic visual scenes for simulated flight.
Another object of this invention is to provide an image generation system which supplies imagery to a projection system in which a dynamic earth/sky interface can be provided at relatively low cost.
Another object of this invention is to provide an earth/sky interface which is dynamically changed in real time with simulated flight movements.
Another object of this invention is to provide an image generation system in which a flat transparency is employed to provide imagery for a projection system for projecting imagery representing the earth surface.
Another object of this invention is to compensate electronically for geometric distortions introduced by a projection system projecting onto a curved surface.
Yet another object of this invention is to provide a system for controlling the sweep voltages of a CRT so as to permit use of a flat transparency for image projection.
Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.